The invention pertains to trailer hitches and more particularly to fifth wheel trailer hitches. More specifically, the invention relates to trailer pin assembly portion of a fifth wheel hitching system.
Fifth wheel trailer hitches have long been used to connect the tractors of semitruck combinations, or smaller trucks, to a trailer. Commonly a fifth wheel trailer hitch system consists of a fifth wheel locking assembly which is mounted on the truck and a fifth wheel trailer pin assembly which is mounted on the trailer.
Conventional fifth wheel trailer pin assemblies consist of a kingpin and skid plate, which are attached to the trailer. When the kingpin enters a jawslot in a fifth wheel locking assembly the locking assembly firmly closes on the kingpin, thus mating the trailer pin assembly and the locking assembly into the complete fifth wheel trailer hitch system.
A problem suffered by conventional fifth wheel hitching systems is that there is no horizontal flex for accommodating siderocking movement about the axis which generally extends from the front of the towing vehicle to the rear of the trailer. Therefore it can be very difficult to couple, or uncouple, the towing vehicle and the trailer when they are at differing cants due to uneven ground. Further, undesirable forces can be transferred from the truck to the hitching system and to the trailer (and vice versa), thus increasing wear and tear on all components and increasing the likelihood of a component failure.
Previous inventors have addressed the lack of horizontal flex in conventional fifth wheel hitching assemblies by devising a fifth wheel locking assembly which is capable of pivoting horizontally as well as vertically. The difficulty with this type of solution is that the locking assembly is the most complex part of the hitching assemble and therefore required a complex invention to add the capability of horizontal flex to the locking assembly.